Seminar Report

A SEMINAR-REPORT FOR THE PARTIAL FULLFILMENT OF B.TECH DEGREE IN MECHANICAL ENGINEERING

HARYANA ENGINEERING COLLEGE (JAGADHRI)

TOPIC: AIR BRAKE SYSTEM OF INDIAN RAILWAYS

SUBMITTED BY:

RAJKUMAR 1804507 MECHANICAL (M1).

SUBMITTED TO: DEPARTMENT OF MECHANICAL ENGG. HARYANA ENGINEERING COLLEGE (JAGADHRI)

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BRAKING SYSTEM INTRODUCTION:-The most vital factor in the running and control of any vehicle whether it is a cycle, scooter, car, bus, or train is the breaking system. In order slow down the moving vehicle in a shorter possible time, the energy of motion possessed by vehicle must be converted in to other forms. During break application in any vehicle the energy of motion is converted in to heat. This u might have noticed at the rim when you apply brakes repeatedly at short intervals.

Brake: brake is an arrangement provided in the vehicle for slowing down or bringing to rest a moving vehicle in the shortest possible distance.

Factor affecting the brake:

The various factor that governs braking

action in any vehicle are :1.

pressure

2.

surface area in contact

3.

kind of material

4.

heat generation.

Basic requirements of brake:Keeping in the view the safety of human life and physical resources the basic requirements of brake are: 1. brake must be strong enough to stop the vehicle during an emergency with in a shorter possible distance. 2. there should be no skidding during brake application &driver must have proper control over the vehicle during the emergency. 3. effectivness of brakes should remain constant even on prolonged application or during descending on a down gradient. 4. brake must keep the vehicle in a stationary position even when the driver is not present.

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Types of braking system:1. VACCUM BRAKE 2. COMPRESSED AIR BRAKE.

VACUUM BRAKE- brake application takes place when vacuum is destroyed by allowing air to enter to the system. During brake application piston is pushed inward.

LIMITATIONS OF VACCUM BRAKE SYSTEM:#

Brake cylinder piston takes longer time to release after each application

of brakes because single train pipe. #

successive brake application on gradients are not effective as piston

takes longer time for release. #

vacuum brakes are not suitable for high speed trains the maximum

pressure available for brake application is only atmospheric. Thebrake power is inadequate for higher loads and speed. #

brake power destroyed over the period of time as train run over long

period.

AIR BRAKE 1. Brake application is takes place when pressure is dropped in brake pipe 2. during brake application the piston is pushed outward.

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SCHEMATIC VIEW OF SINGLE PIPE AIR BRAKE SYSTEM

CLASSIFICATION OF BRAKING SYSTEM Various type of brake systems are available for passenger coaches such as: 1. Direct release air brake system Graduated release air brake system 2. Direct and graduated release are further available in two forms viz.

- Single pipe -

Twin pipe

DIRECT RELEASE AIR BRAKE SYSTEM Direct release air brake system is not suitable for Indian condition because of variable gradient enroute (critical sections).

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GRADUATED RELEASE AIR BRAKE SYSTEM Graduated release air brake system is most suitable for Indian railways. Operation of graduated release air brake system consists of following stages: * Charging * Graduated Application and Emergency application * Graduated Release *For application of brakes pressure in brake pipe is dropped . * Magnitude of braking force is proportional to reduction in brake pipe pressure.

* Various stages of brake application are - Minimum application - Service application - Full service application - Emergency application

* As compared to single pipe graduated release air brake system twin pipe graduated release air brake system is more suitable for passenger coaches

The twin pipe graduated release air brake system consists of following components:1. Distributor valve 2. Common pipe bracket with control reservoir 3. Auxiliary reservoir(200lts) 4. Three way centrifugal dirt collector 5.Isolating cock 6. Check valve with choke 7. Brake cylinder (355 mm diameter)

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8. Cut of angle cock(25 mm feed pipe )size on either ends of brake pipe as well as 9. Air brake hose coupling (32 mm for brake pipe ) 10. Air brake whose coupling (32 mm for feed pipe) 11. Passenger emergency alarm valve 12. Passenger emergency signal device with resetting key 13. Brake pipe and feed pipe (25mm dia.) 14. Branch pipes from BP and FP to brake equipment (20 mm bore) 15. Branch pipe connecting passenger emergency alarm valve and passenger emergency alarm signal device(10 mm bore) 16. Guard emergency brake valve 17. Pressure gauges for BP and FP

Air Brake System In it, compressed air is used for operating the brake system. The locomotive compressor charges the feed pipe and the brake pipes throughout the length of the train,. The feed pipe is connected to the auxillary reservoir and the brake pipe is connected to the brake cylinder through the distributor valve. Brake application takes place by dropping the pressure in the brake pipe.

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Schematic view of twin pipe air brake system



Principal of operation: -

(1) Charging the brake system.

 

Brake pipe throughout the length of the train is charged with compressed air at 5kg/sq.cm. Feed pipe throughout the length of the train is charged with compressed air at 6 kg/sq. cm.



Control reservoir is charged to 5kg/sq.cm.



Auxiliary reservoir is charged to 6kg/sq.cm.

(2)

Brake applicant stage: 7

    (3)

 

For brake applicant the brake pipe pressure is dropped by venting air from the drivers brake value subsequently the following a chain takes place. The control reservoir is disconnected from the brake pipe. The distributor value connects the auxiliary reservoir to the brake cylinders and the brake cylinders piston is pushed outwards for applicant of brakes. The auxiliary reservoir is however continuously charged from feed pipe at 6Kg 1cm2.

Brake release Stage: Brake are released by recharging pipe 5Kg2 pressure through the drivers brake value The distributor value isolated the brake cylinders from the auxiliary reservoir.

The brake cylinder through pressure is vented to atmosphere through DV and the brake cylinders piston moves in words.

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ADVANTAGES OF AIR OVER VACCUM BRAKE:-

Parameters

Air Brakes

Emergency braking distance (4500 t level track, 65 kmph)

632m

Brake power fading

No fading

Weight of equipment per wagon (approx.)

275kg

Pressure Gradient

Preparation time in departure yards (45 BOX or 58 BOXN)

Vacuum Brakes

1097m

At least by 20%

700kg

No appreciable difference Steep reduction in in air pressure between vacuum in trains longer locomotive and brake van than 600m. up to 2000m.

Less than 40 minutes.

Safety on down gradients

Very safe

Overall reliability

Very good

Up to 4 hours.

Needs additional precautions

Satisfactory

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